Internal Revenue Service, which has lost 30% of its enforcement staffing since 2010, audited 0.7% of tax returns in fiscal year ended Sept. 30

WASHINGTON—U.S. tax audits of individuals declined for the fifth straight year in 2016 to reach the lowest level since 2003, showing the effects of budget cuts at the Internal Revenue Service.

The IRS, which has lost 30% of its enforcement staffing since the 2010 peak, audited 0.7% of tax returns in the fiscal year that ended Sept. 30, according to preliminary data released Wednesday. That means the IRS audited roughly 1 in every 143 individual tax returns, down from 1 in 90 back in 2010.